If you were making an admiring biographical drama about Edward Snowden, CIA wunderkind turned NSA whistleblower, which criticism of its subject would you be keenest to debunk? Other filmmakers might have tackled the argument that Snowden’s seismic 2013 leak of classified government documents, however well-intentioned, recklessly damaged national security in the United States and elsewhere – or that his subsequent holing up in Vladimir Putin’s Russia sits ill with his condemnation of state-sponsored mass surveillance.

But for Oliver Stone, the main bone of contention in the Snowden story seems to be the doubt that an IT wizard can be just as much of a red-blooded, gung-ho patriot as anyone else. As such, it’s his subject’s macho credentials, rather than political and ethical motives, that his film sets out to defend with grimacing determination.

Snowden is the 20th feature in a politically charged career that has ranged from Wall Street and JFK to the mind-numbing doldrums of his recent war-on-drugs thriller Savages. But Stone’s fixation on the sheer dang manliness of sticking one to the government, even digitally, feels misguided here from the off. This is a work of crude and jangly bombast, forever phonily cranking up the stakes with sex, techno music and drive-by swipes at Obama, and which seems bored by the deeper implications of its subject’s extraordinary choices.

Take the moment that, for no conceivable reason other than the obvious, the film packs off its hero, played by Joseph Gordon-Levitt, on an undercover CIA mission at a strip club, before sending him home the next minute – and in film-time, it literally is the next minute – to make acrobatic love with his naive but nubile girlfriend Lindsay (Shailene Woodley, working with nothing), who also happens to be a pole dancer.

If these are attempts to make us warm to the film’s not immediately likeable lead character, they’re oddly self-defeating ones – not least because during the moonlit sex scene, Snowden panics about being spied on via some hijacked camera in his room, which is exactly what the film itself is up to. But Gordon-Levitt still gives it his best shot.

His creaky-floorboard baritone, much derided in the film’s trailers, works better in context than you might think – it feeds the sense we have of him as a man constantly wary that his words and actions are being monitored.

There’s not a great deal for him to mine out of the screenplay, which was adapted by Stone and Kieran Fitzgerald from a couple of books, one of which is a fictionalised biography about a US whistleblower called Joshua Cold, written by Snowden’s Russian lawyer. The film begins with Snowden’s clandestine arrival in Hong Kong in the days before the leak.

In an anonymously stylish hotel room, the door muffled by pillows, he tells his story to a trio of journalists – documentary filmmaker Laura Poitras (Melissa Leo), Glenn Greenwald (Zachary Quinto, best known as Star Trek’s rebooted Spock) and the Guardian’s Ewen MacAskill (Tom Wilkinson). Then time spools back to 2004 and Snowden’s US Army training, before bouncing back and forth until the past catches up with the present.

Joseph Gordon-Levitt and Shailene Woodley

The hotel room conversations are the basis for a great, existing Snowden film: Poitras’s Oscar-winning 2014 documentary Citizenfour, which captured the white-hot panic of his actions in mesmeric detail, while also setting them meticulously in context. There is a fantastically self-important moment here in which Snowden asks Poitras turn off her camera so he can talk less guardedly: ie, in Stone’s fictional version of events, he gets some juicy details she didn’t.

Like Charlie Sheen’s beguiled-then-conscience- stricken broker in Stone’s 1987 film Wall Street, Snowden’s story as told by Stone is one in which moral enlightenment comes via a sustained spell behind the curtain in the Wizard’s throne room.

Appropriately, as Snowden’s slippery CIA mentor – a kind of Gordon Gekko lite – Rhys Ifans even has a scene in which his face is projected, in Great Oz-rivalling dimensions, onto the wall of a board room during a pivotal Skype call. It’s the kind of merrily ludicrous moment that, had it been built on rigorous drama rather than self-indulgent bluster, you’d go home raving about.